Telescopic tubular splined assembly

Telescopic tubular assembly comprising:

• at least one larger diameter first tubular section (1) and one smaller diameter second tubular section (2) having an inside end (4) housed inside the first tubular section (1) and able to rotate freely and to slide inside the first tubular section (1) between a retracted position and a deployed position,
• an actuator device comprising a first actuator member sliding in the larger diameter first tubular section (1) and comprising a second actuator member fixed to the smaller diameter second tubular section (2), the first actuator member and the second actuator member cooperating with each other in the manner of a screw in order to displace the first actuator member axially upon relative axial rotation,
• an expandable locking member sliding axially in the larger diameter first tubular section (1), constrained to move in axial translation with the smaller diameter second tubular section (2) and being capable of expanding or retracting radially when the first actuator member moves axially,
• the interior surface (5) of the larger diameter first tubular section (1) comprising at least three equi-angularly distributed longitudinal ribs (6, 13, 14) extending along all or the major part of its length and each engaged in a respective longitudinal peripheral locking groove (15, 16, 17) of the expandable locking member to lock it against rotation,
• the interior ribs of the first tubular section (1) being formed by depressing the wall of said tubular section to form simultaneously longitudinal exterior grooves (18, 19, 20) which are narrower than the interior ribs (6, 13, 14),
• characterized in that:
• the second tubular section (2) comprises similar interior ribs and exterior grooves, its exterior grooves (21, 22, 23) being narrower than the interior ribs (6, 13, 14) of the first tubular section (1) to prevent their mutual interengagement,
• the ribs (6, 13, 14) of the first tubular section (1) are shaped to bear with a small clearance and simultaneously against the exterior surface of the smaller diameter second tubular section (2),
• said ribs (6, 13, 14) of the first tubular section have a wide and rounded concave outermost surface to mate with a significant portion of the exterior surface of the second tubular section (2) and to constitute between the tubular sections (1, 2) a bearing surface adapted to withstand mechanical bending loads exerted on the telescopic tubular assembly.